(*
This file is part of the Lustre reader

* Copyright (c) 2010, Nicola Camuffo* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
*       notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       documentation and/or other materials provided with the distribution.
*     * Neither the name of Nicola Camuffo, nor the
*       names of its contributors may be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*)


open Lustypes
open Utils
open Exceptions


type _env = _id

let environments = new stack


(* catches-and-throws *)
let cat f msg =
	try
		f ()
	with exn -> raise (Environment_exception (msg,Some exn))


(* returns last environment in the stack *)
let current_env () =
	let msg = "No open environments" in
	cat (fun _ -> environments#top ()) msg

(* adds a new environment in stack *)
let open_new_env = environments#push

(* removes last environment from stack *)
let close_env () =
	let msg = "No open environments" in
	cat (fun _ -> environments#pop ()) msg

(* gets nth environments from last to first *)
let get_nth_env n =
	let msg = "Not enough open environments" in
	cat (fun _ -> environments#get n) msg
